Notes about Mini Marcos 7000 - 270 DGJ

Words and pictures by Billy Dulles

Built up from new components and assumed the identity and log book of a
1961 997 Mini Cooper, which by that time had a new 1275 Cooper S unit
installed.

The 'donor car' was getting rather loose as it had pounded up and down
the Alps all the time I was a student at Grenoble U. and used as a practice
mule when I went hill climbing my Lawrencetune Morgan Plus 4.

Jem Marsh supplied the shell on loan as a demonstrator and after building
and painting (Marigold and Matt black) the car went back to Bradford-on-Avon
to be trimmed. We felt we should have a well finished demonstrator to show
rather than a bare shell in gel-coat, in anticipation of any interest after
Le Mans. The mould was generally cleaned up, with semi-circular wheel
arches, slide up windows, but no recessed filler cap. The passenger doors
made the same length. There was a difference of I think 3/4" on the Mk 1
cars. I refer to it as the first of the Mk IIs, but don't recall the chassis
number. Andy Seward thinks it was #7000.

We had a large alloy fuel tank made for the lightweight car, (written off
on the way to Mugello) by Peel Bros. of Kingston. I made a dimensioned
sketch of an inverted 'L' shaped tank with the footprint of the Mini Van
tank, gave the van tank as a pattern and a few days later had a phone call
to tell me that my tank was ready. This was later fitted to 270 DGJ for
Mugello and the Nürburgring. The filler cap was a large alloy Enot's
bought from the people who made them for Double-decker buses.

The Peel brothers were renowned for making wonderful racing motorcycle
fuel tanks with cut outs for the bars and notches for the rider's
knees. Their welding and craftsmanship was unbelievable. They had made so
many GP Bugatti bodies for vintage racing that legend said they would start
wheeling and beating metal a soon as you put the phone down to order one!

The bucket seats came from Terry Hunter's firm. Can't remember what they
called themselves but they were next to John Sprinzel's Garage, in Brook
Mews, Paddington and although they were agents for Rocaro, sold oil coolers
and go faster tape, they produced a cheap bucket seat which had the
advantage of being light and comfortable. I think Sprinzel had had some
input into the design.

We set out for Mugello with a set of brand new Minilites but some were
never recovered in the crash. Maybe some lucky farmer on Wrotham Hill now
has a farm trailer with Minilites & Dunlop R6. Once bought a farm cart
in Alsace which sported GP Bugatti wheels and axles, but that is another
story. Any way the Mugello pictures show us on steel wheels, and as we had
to run them on the road, and competed in a hill-climb on the way home, they
were pretty well bald by the time we got to UK. The car ran on steel wheels
at the 'Ring also, so we obviously did not have a complete set of alloys.

As for engine tuning, we couldn't really improve on the cylinder heads
produced by Daniel Richmond's Downton Engineering. Dished forged pistons 40
thou' oversize which we ovalised by careful hand filing. We balanced the
bottom end and machined off a judicious amount of weight from the clutch
driven plate and flywheel; Too much and you shed the starter ring gear. We
used a 12-1/2 to 1 compression ratio, sometimes 13 to 1, but it still ran
on, on shut down, despite 108 Octane petrol. The Italians did not seem to
have this problem and we discovered that they were drilling holes into the
water passages in the head under the rocker posts, to remove pieces of sand
core and coring wires, and then brazing the holes up again. Why didn't we
think of that? Close ratio straight cut gears from Special Tuning were de
rigueur, but we had the Colloti 5 speed, which was enormous fun, like a
motorcycle box, no synchro., just dog clutches and very close ratios. A ZF
limited slip differential made sure we got the power to the little
Dunlops. The single Weber 45 DCOE was more practical than twin 1½" SU
some people went to 1¾". Once the jetted properly with the correct
venturis and tuned for tick-over it was bullet proof.

Cooling was a major preoccupation. We had a cross-flow radiator in the
front made from an early perpendicular Ford Popular core and custom top and
bottom tanks (side to side) fed from a Triumph Herald header tank and 13lb
cap. A 13 row oil cooler took care of lubricant temperature. We always used
Castrol R and I favored the old fashioned felt filter elements as it seemed
to trap metal debris better than the paper ones. The magnetic sump plug was
there for a purpose and sharing the gearbox and engine oil was not the best
way of keeping the iron filings from the gear train out of the bearings. A
central oil pick up was necessary otherwise oil pressure flew off the gauge
on right hand corners (or was it left?) but if you half filled the sump you
got about five extra horses from not churning the oil in the gearbox. We
even tried a semi dry sump configuration. The 649 camshaft has a second skew
gear on it, where the standard cam has an eccentric for a mechanical fuel
pump. There is a machined pad on all 'A' series blocks for the fuel
pump. And guess what, an oil pump from a prewar Wolseley Hornet bolts
straight on and meshes with the cam gear, to be used as a scavenge pump
which is arranged to pick up from the bottom of the gear case leaving 2 or 3
pints for the gears and differential. The pressure pump feeds from a remote
tank and you can carry more oil that way. Nowadays I suspect that you can do
this off a belted cam drive, much simpler.

That was basically the end of that season, although I did not know it at
the time. I had entered for Monthlery, outside Paris, but couldn't go as I
had to give Tim my engine in return for blowing up his. I got an entry for
Clermont Ferrand with Mike Pigneguy's ex Le Mans Sprite, but after towing
the car all the way we seized in practice and so that was that.